tmp/tmpajkyhrnm/{from.md → to.md}
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#### Value status <a id="variant.status">[[variant.status]]</a>
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``` cpp
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constexpr bool valueless_by_exception() const noexcept;
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```
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*Effects:* Returns `false` if and only if the `variant` holds a value.
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[*Note 1*:
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A `variant` might not hold a value if an exception is thrown during a
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type-changing assignment or emplacement. The latter means that even a
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`variant<float, int>` can become `valueless_by_exception()`, for
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instance by
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``` cpp
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struct S { operator int() { throw 42; }};
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variant<float, int> v{12.f};
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v.emplace<1>(S());
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```
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— *end note*]
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``` cpp
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constexpr size_t index() const noexcept;
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```
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*Effects:* If `valueless_by_exception()` is `true`, returns
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`variant_npos`. Otherwise, returns the zero-based index of the
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alternative of the contained value.
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